Modulated signals often face distortion and interference during transmission. Radio frequency (RF) transmissions are particularly susceptible to distortion and interference. This is particularly true when considered against the backdrop of the entire RF frequency spectrum. Even when just considering a wideband portion of the entire spectrum, received bandwidths can be sufficiently large so that direct digitization of the entire bandwidth is simply not feasible using existing analog-to-digital conversion technology. Large information bandwidths (such as around 1 GHz) burden analog-to-digital converters and/or digital signal processors.
While certain signal processing techniques can assist in limiting distortion and interference, the fact remains that narrowband gain elements in the tens of Megahertz do not exist in the RF domain. Additionally, existing Raman narrowband optical gain techniques fail to include a notch filter capacity, and also use a large amount of laser pump power. Other techniques also pose problems. For instance, the usage of an Erbium Doped Fiber Amplifier (EDFA) fails to include a notch filter capacity, and also uses large amounts of laser pump power. Further, EDFA is wideband which lends itself to amplification of noise and interference along with desired signals.